Congressional bargainers met with top administration officials last night in a search for compromise over aid to Nicaragua's Contra rebels, the main issue blocking completion of two huge budget bills.

With a full government shutdown looming tomorrow, Democratic leaders traded offers with White House Chief of Staff Howard Baker, Treasury Secretary James Baker and President Reagan's national security adviser, Colin Powell.

Democrats also discussed a temporary spending bill to keep agencies operating tomorrow if the talks dragged. "That's not the plan. It might come to that, though," said House Speaker Jim Wright.

Chief of staff Baker said during a break in the talks that he was hopeful a deal could be struck.

"I think there's movement," said Sen. Ted Stevens, R-Alaska, who has served as a point man for the administration on the Contra issue.

The president used his Saturday radio address to make another pitch for money for the Contras, citing boasts by Nicaragua's communist government about building up a 600,000-member military force by 1995.

"It's clear to all but the most naive that the Sandinista communists have been cynically manipulating the peace process, trying to lull others into a false sense of security while they busily plan military dominance of the entire region," Reagan said.

"It has has never been more clear why we must fund the freedom fighters," Reagan said. When deciding whether to sign the budget bills, "one item that we will be looking very closely to see included is funding for the freedom fighters in Nicaragua," he said.

The president did not mention a specific figure on how much Contra aid he wanted.

The administration sought $22.8 million, then supported a Senate provision giving the Contras $9 million in non-lethal aid and allowing the Central Intelligence Agency to deliver arms along with the food and clothing. The House has approved no money, but leaders have offered to compromise if some limits were placed on CIA deliveries.

"Whatever the center of gravity is, the conferees will find it," Byrd said.

But other Democrats were growing frustrated with the talks, which lasted into the night.

"The White House is pulling back offers that it already made," said Rep. David Obey, D-Wis., chairman of a foreign policy subcommittee. Obey said House Speaker Jim Wright, D-Texas, was ready to compromise but "he's in no mood to be rolled," he said.

House Budget Committee Chairman William H. Gray III, D-Pa., said the big problem was that liberals in the House would not support anything close to the administration position on Contra aid. "It just won't fly," he said.

An aide to Wright suggested yesterday that if no compromise is reached, House and Senate Democrats might work out their own deal on Contra aid, then seek to pass the legislation and let the president decide whether to veto it and bring the government to a halt.

That legislation would also likely include the Fairness Doctrine, canceled earlier this year by the Federal Communications Commission, which requires broadcasters to present controversial issues in a balanced way. Reagan has previously vetoed similar, free-standing legislation aimed at making the fairness doctrine a law and has vowed to veto the huge spending bill if it includes the broadcast standard.

The Contras and the fairness doctrine were attached to the mammoth $600 billion spending bill for fiscal 1988. The measure, an amalgam of what would normally be 13 separate appropriations bills for the year that began Oct. 1, covers all facets of government spending from nuclear weapons to food for the hungry.

The spending in the bill, while bigger than any previous bill, was held $7.6 billion below normal inflationary increases as part of the $76 billion, two-year deficit reduction agreement between the president and congressional leaders.

The bulk of the more than $30 billion in fiscal 1988 deficit reduction was found in the companion budget bill. That measure would raise more than $9 billion in taxes this year, cut costs in farm and entitlement programs, and sell off government assets to trim the deficit a total of $22.6 billion.

There were several remaining issues in that bill, including proposed cuts in postal spending and Medicare, but House Majority Leader Thomas S. Foley, D- Wash., said he saw progress in working those out.

Sen. Lloyd Bentsen, D-Texas, chairman of the Senate Finance Committee, said an agreement on Medicare cost-cutting was at hand but Medicaid program changes remained at issue. Asked if talks could finish by last night, he said, "I think it's going to be very difficult. We've got lots of problems."

Medicare is the federal health insurance program for the elderly and disabled. Medicaid is the federal-state program primarily for the needy.